Electrical apparatus



May 17, 1960 J. F. LUDWIG ELECTRICAL APPARATUS 2 Sheets-Sheet 1 Filed Dec. 26, 1957 l N V E NTO R JAMES F- LUDWIG BY 5 M 4% ATTORNEYS May 17, 1960- J. F. LUDWIG ELECTRICAL APPARATUS 2 Sheets-Sheet 2 Filed Dec. 26, 1957 NVENTOR JAMES F. LUDWIG ATTOR NEYS United States Patent ELECTRICAL APPARATUS James F. Ludwig, Unadilla, N.Y., assignmto l 3endlx Aviation Corporation, Sidney, N.Y., a corporation of Delaware Application December 26, 1957, Serial No. 705,377

g 17 Claims. (Cl. 219-32) This invention relates to electrical apparatus, and more particularly to an electrically operated igniter unit designed for operation at high temperatures.

The invention has among its objects the provision of a novel electrically operated igniter unit designed for operation at high temperatures.

A further object of the invention resides in the provision of an electrically operated igniter unit having a novel arrangementv and orientation of parts whereby it may operate without damage thereto for long periods under conditions in which it is subjected tov marked vibration at elevated temperature.

Yet another object of the invention lies in the provision of an electrically operated igniter unit having a novel chassis and housing structure.

Still a further object of the invention lies in the provision of an electrically operated igniter unit including a novel mechanism for mounting the unit on a support such as a jet, ram-jet, or other engine or the like which subjects the unit to marked vibration and elevated temperature. t

The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts through the several views,

Fig. l is a view in horizontal longitudinal, generally axial section through an allustrative embodiment of igniter unit made in accordance with the invention, the component parts of the igniter unit within the housing being shown generally in plan;

Fig. 2 is a view in vertical longitudinal, generally axial section through the igniter unit of Fig. 1, the component parts of the igniter unit within the housing being shown in side elevation;

Fig. 3 is a view in transverse section through the igniter unit, the section being taken generally along the line 3-3 of Fig. 1;

Fig. 4 is a view in transverse section through the igniter unit, the section being taken generally along the line 4-4 of Fig. 1, a supporting means for the unit being shown associated therewith.

The igniter unit of the present invention may be used, for example, to start combustion in a jet or ram-jet engine. Because of the need for economy of space, as well as to reduce the length of electrical leads therefrom, the igniter unit is preferably mounted upon the casing of the engine which it is to serve. This subjects the igniter unit, however, to very severe operating conditions, since the housing of the engine when operating becomes highly heated and such housing vibrates markedly during operation of the engine. A successful igniter unit for a use such as that above outlined must, therefore, be able to operate for long periods at elevated temperatures, and

must be able to withstand marked vibrations while at elevated temperature. In addition, since the use of the engine requires that it be heated from atmospheric or ambient temperature to an elevated temperature when the engine is started, and that it be cooled from the elevated temperaure to amospheric temperature when the engine is stopped, the igniter unit must be able to stand repeated marked changes in temperature and be able to absorb or compensate for dimensional changes in the parts, including the means mounting the various components in the igniter unit, and the means mounting the igniter unit on its support.

The igniter unit of the present invention includes components which may be connected in an igniter circuit such as that shown and claimed in the application of London, Serial No. 665,558. Since the circuit is not a part of the present invention, it is not here shown.

Turning now to the drawings, the igniter unit as a whole is generally designated by the reference character 10. The unit is supported, for example, on the housing of a ram-jet engine (not shown) by one or more clamping band members made up of halves 16 (Fig. 4), ears 17 of the clamping members being connected as by a stud 18 to supporting pedestals, of which one is shown at 15 in Fig. 4, attached to the engine housing. Such supporting members, except for the wires leading into and from the unit, constitute the sole mechanical connection between the igniter unit and its support. Such supporting members make contact with the housing of the unit. The housing and the frame therewithin supporting the electrical components making up the igniter circuit, are designed to minimize the passage of heat from the engine housing to the igniter unit, to yield upon changes of dimensions of the various parts attendant upon changes in temperature of the igniter unit and the engine housing, and to minimize the transmission of vibrations from the engine housing to the components of the igniter clrcuit.

The igniter unit has a generally circular cylindrical housing 14, the ends of the housing being closed by flanged disc-like end closure members '11 and 12 welded thereto. The components of the igniter circuit are disposed within the housing, in a manner to be described, so as generally to be spaced from both the side wall and the end walls thereof. Consequently, such circuit components receive heat from the engine only by conduction through the supporting means to the housing 14. To minimize the fiow of heat inwardly to the circuit components, the space within housing 14 surrounding such components is filled with heat insulating material 46, such as magnesia and the like. Electrical connections to the unit within the housing are made by means of a first and a second, delivery terminal fitting, of which parts are shown at 19 and 20, attached to end member 11, and a third, input terminal fitting, of which a part is shown at 21, attached to end member 12. s Support for the circuit components within the housing is provided by aligned opposed similar sets of brackets laterally centrally secured to the inner walls of the end members of the housing, Such brackets are arranged in upper and lower pairs, the upper and lower brackets at end member 12 being designated 22 and 22, respectively, and the upper and lower brackets at end member 11 being designated 24 and 24, respectively. The brackets of each pair, in the embodiment shown, are mirror images of each other. The sets of brackets at the respective end members are also mirror images of each other.

The shape of the brackets 22, 22' 24, and 24' will be understood upon a consideration of Figs. 1 and 2. Each of the brackets is bent from sheet metal, and is of semihooded shape so as to be reinforced against vertical and sidewise forces. The base of each bracket is attached, as by welding, to the respective end member of the housing. Each bracket has the inner portion thereof of a truncated trianguler shape in plan (Fig. 1) the laterally outer faces of the brackets of each pair being parallel to each other and lying in planes parallel to the longitudinal axis of the housing. The vertical outer faces of corresponding brackets 22, 22, and 24, 24' lie in vertical alignment with each other, as shown.

The circuit components of the igniter unit are mounted on a longitudinally extending frame composed of four similar elongated angle members which have their opposite ends supported by corresponding confronting brackets 22, 24 or 22, 24', as the casemay be. The upper two angle frame members, designated 26 and 27, have one flange 32 thereof disposed vertically and the other flanges 31 of the respective upper frame members projecting laterally outwardly in opposite directions in their common horizontal plane. The two lower frame members, designated 29 and 30, respectively, are each disposed with one of their flanges 31 disposed horizontally and the other flange 32 disposed vertically, flanges 31 projecting laterally in opposite directions in their common horizontal plane from flanges 32.

Each of frame members 26, 27, 29, and is disposed with its ends spaced laterally outwardly of its supporting brackets 22, 24, etc. Interposed between the broad vertical face of each bracket and the confronting end of the frame member is a metal strap-like member 34 which has its opposite ends 23 laterally offset from each other and lying parallel to the vertical axial plane of the housing. The intermediate portion of member 34 extends angularly across the space between the vertical face of the bracket and the vertical flange of the frame member. Ends 23 of member 34 are rigidly secured, as by welding, to the vertical face of the bracket and the vertical flange of the frame member. Preferably, as shown, the direction of inclinations of the respective members 34 at one end of the housing are the same, such direction of inclination being opposite to each other at the opposite ends of the housing.

The relatively narrow strap-like members 34 constitute the only mechanical connections, other than the lead wires, between the housing, and its support, and the frame composed of members 26, 27, 29, and 3t) and the circuit components carried thereby. As a result the rate of flow of heat inwardly to the frame and circuit components is relatively slow. Consequently, the circuit components do not become heated to an undesirably high temperature despite the operation for extended periods of the highly heated ram-jet engine to which the igniter unit may be attached. In addition to the above described advantage of the low rate of heat flow to the circuit components, members 34 are also advantageous in that they provide a very good shock-absorbing mounting for such circuit components. Thus, since members 34 are mounted so that the weight of the frame members 26, 27, 29, and 30 and the circuit components supported thereby place them in shear, they are relatively free to flex so as to allow the frame to move laterally to cradle the circuit components against vibrations to which the housing of the igniter unit is subjected. The symmetrical positioning and inclination of the bodies of members 34 tends to maintain the frame symmetrically and centrally within the housing.

The frame members 26, 27, 29, and 30 support circuit components including a filter unit 35, resistor units 33, two transformers 36, condenser units 37, rectifier units 40, and control gaps 45. The circuit components, and/or their imediate mounting or supporting means, serve to connect the frame members together as a unit. As will be seen, the resistor units 33 comprise box-like housings supported between the vertical flanges of the upper and lower pairs of frame members, respectively,

and connected thereto by spacer members 41. The filter unit 35 is mounted generally centrally within the four frame members. The two transformers 36 are mounted upon braced oppositely disposed channel members 38, as best shown in Fig. 3. The inner, vertical web portions 42 of the respective members 38 are parallel, the flanges 44 of members 38 being secured, as by welding, to the horizontal flanges of the respective frame members, which they abut.

The condenser units 37 are mounted within the space between the frame members and are secured thereto by interposed sheet metal brace members 39, as shown most clearly in Figs. 2 and 4. The rectifier units 40 are mounted in box-like sheet metal cases which are disposed between the horizontal flanges of the frame members at each side of the frame, as shown in Fig. 4. The two control gaps 45 are mounted in housings disposed one above the other and transversely of the frame. As shown in Fig. 2, the control gap housings are connected together by a sheet metal cage member 46, such cage member being positioned between and secured to the upper and lower frame members.

The igniter unit may be assembled by mounting the brackets 22, 24, etc. on the inner faces of the end members, after which the frame members 26, 27, etc., are attached to brackets through the medium of strap-like members 34. The components of the igniter circuit may now be mounted upon the frame, and the wiring of the circuit completed. The thus assembled frame and end members may now be telescoped within housing 14, preferably in a direction from left to right in Fig. 1, since end member 11 is made with a diameter somewhat smaller than end member 12, to facilitate such manner of assembly of the unit. Before the assembled frame, components, and end members are fully telescoped within housing 14, the heat insulating material 46 is charged into the space between the housing and the inner assembly. Following this, the inner assembly is moved to its final, fully telescoped position within the housing, and the end members are secured and sealed, as by being edge welded, to the ends of housing 14.

Although only a limited number of embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing specification, it is to be expressly understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the invention as will now be apparent to those skilled in the art.

What is claimed is:

1. An electrically operated igniter adapted to operate at elevated temperatures, comprising two spaced parallel end members, a plurality of spaced inwardly extending brackets on the end members, a plurality of spaced longitudinally extending frame members extending between the brackets on the respective end members, resilient members connecting the ends of the frame members to the brackets, and a plurality of units which contain at least some of the elements of the igniter circuit suspended upon the frame members.

2. An igniter as defined in claim 1, wherein the ends of the frame members are spaced laterally from the respective brackets, and the resilient members are interposed between the brackets and the frame members.

3. An igniter as defined in claim 2, wherein the resilient members are strap-like, extend angularly between the brackets and the frame members, and have their respective ends secured to the brackets and frame membe's.

4. An igniter as defined in claim 3, wherein all the strap-like resilient members are disposed with their respective opposite lateral edges facing in the same directions.

5. An igniter as defined in claim 4, wherein the planes of the broad extents of the strap-like resilient members lie vertically.

6. An igniter as defined in claim 1, comprising a rigid casing disposed around the frame members and the units supported thereby, the casing being rigidly connected to the end members.

7. An igniter as defined in claim 6, comprising a substantial thickness of heat insulating material disposed within the casing and between it and the end member and the units.

8. An igniter as defined in claim 6, wherein the end members are sealed to the casing.

9. An igniter as defined in claim 6, wherein the brackets and frame members are disposed adjacent the commo'n axis of the end members and symmetrically with respect thereto, and the units are located a substantial distance from the inner wall of the casing.

10. An igniter as defined in claim 9, comprising a substantial thickness of heat insulating material disposed within the casing and between it and the end members and the units.

11. An igniter as defined in claim 1, wherein there are four frame members symmetrically disposed in sets of two on opposite sides of the longitudinal axis of the igniter, the frame member being L-shaped in section, the corresponding flanges of the frame members of each set being parallel, the resilient members being connected to the vertically disposed flanges of the frame members of each set.

12. An igniter as defined in claim 11, wherein the brackets are located laterally between the two sets of frame members, each bracket has a vertically disposed surface located inwardly of and parallel to the end of the vertical flange of the respective frame member, and the resilient members are in the form of straps having parallel laterally offset end portions secured to the vertical surface of the bracket and the end of the vertical flange of the respective frame member.

13. An igniter as defined in claim 12, wherein the straps at one end of the igniter are laterally offset in a direction opposite from that of the straps at the other end of the igniter.

14. An igniter as defined in claim 11, wherein at least one of the units is supported on the frame members by means comprising a first broad channel member having parallel sides and a broad bottom, the sides of the first channel member fitting inwardly of and secured to the flanges of two frame members lying in the same plane, the said one unit being secured to the bottom of the first channel member between said sides of the first channel member.

15. An igniter as defined in claim 14 comprising a second broad channel member similar to the first broad channel member, said second channel member being disposed oppositely from the first channel member and having its sides fitting inwardly of and secured to the flanges of the remaining two frame members, and another unit secured to the bottom of the second channel member between the sides of the second channel member.

16. An igniter as defined in claim 15, wherein at least one of the units comprises a rigid ho'using positioned laterally outside the corresponding side walls of the two broad channel members and between the flanges of one set of spaced frame members, and means securing said housing to said horizontal flanges.

17. An igniter as defined in claim 11, wherein at least one of the units is positioned with at least a major part thereof laterally outside the vertical flanges of two vertically spaced frame members, the unit is positioned vertically between the horizontal flanges of one set of vertically spaced frame members, and means securing said housing to said horizontal flanges.

References Cited in the file of this patent UNITED STATES PATENTS 2,355,169 Lehman et al Aug. 8, 1944 2,485,496 Korsgren et a1 Oct. 18, 1949 2,756,368 Gross et al July 24, 1956 FOREIGN PATENTS 567,323 Great Britain Feb. 8, 1945 

